The invention relates to ventilation and more specifically to space ventilation and affirmative control of consequential drafts through ventilation ducting.
Situations of using a fan to conduct air or other gases from or into a space are frequent and commonly known. In residential buildings, one may find a bathroom exhaust fan, a kitchen ventilation hood and the like, a water heater exhaust fan, and a furnace exhaust fan, for example. Commercial applications include at least the same situations. In some of these fan and ducting installations, a flap damper may be included to limit back drafting as one having ordinary skill in the art knows. The flap damper is typically minimally effective, however, as is also well known. Further, the flap damper is not designed in consideration of blocking a known chimney effect by which conditioned air may bleed outside a space. Each of these shortcomings of known applications of a fan with ducting are expensive and environmentally hostile as is known to one having ordinary skill in the art.
Thus, a need for a fan with damper that affirmatively controls duct ventilation flow is readily understood.